406 ROSACEAE 



about 20. Achenes inclosed in the calyx, short-stipitate, long-hairy, membran- 

 aceous, indehiscent, caducous, strongly arched on the lower suture; seeds broadly 

 oblong, with a double coat. [Holodiscus Maxim.] 



Leaves grayish- or whitish-tomentose and villous beneath. 



Inflorescence ample, well-compound ; leaves usually over 3 cm. long. 



Leaf-blades abruptly contracted below, scarcely decurrent on the petioles, 4-10 



cm. long. 1. S. discolor. 



Leaf-blades cuneate at the base and distinctly decurrent on the winged petioles, 



2-5 cm. long. 2. S. dumosa. 



Inflorescence small and narrow, simple, racemose, oi % with a few short, spreading 

 branches; leaves usually less than 2 cm. long, finely pubescent and green above, 

 white silky-villous and tomentose beneath. 3. S. microphylla. 



Leaves glandular-atomiferous and slightly hairy on the veins beneath, not at all tomen- 

 tose, 1-1.5 cm. long, glabrous or sparingly pubescent. 4. S. glabrescens. 



1. S. discolor (Pursh) Rydb. Shrub 1-4.5 m. high; leaf-blades rounded- 

 ovate or oval, usually double-toothed, with broadly ovate, mucronate teeth, 

 acute at the apex, truncate, rounded, or cuneate at the base, 4-10 cm. long, thin, 

 green and sparingly pubescent, or in age glabrate above, more or less densely 

 villous and tomentose beneath; inflorescence conical or ovate, 10-20 cm. long, 

 twice or thrice compound; sepals oblong; petals white, elliptic, 1.5 mm. long or 

 more; stamens 15-20; pistils usually 5; carpels semi-ovate, 1-5 mm. long. Holo- 

 discus discolor (Pursh) Maxim. H. ariaefolius (Smith) Howell. Hills and river 

 banks: B.C. Cal. Ida. w Mont. Submont. Je-Au. 



2. S. dumosa (Nutt.) Rydb. Shrub 6-10 dm. high; leaf-blades obovate, 

 2-5 cm. long, obtuse or acute at the apex, often double-toothed above, green 

 and short-hairy above, white and densely villous and tomentose beneath; inflor- 

 escence usually t\vice compound, ovoid, 5-20 cm. long; sepals ovate or lance- 

 ovate; petals elliptic or oval, about 2 mm. long; stamens about 20; pistils 5; 

 carpels about 1.5 mm. long. H. discolor (Nutt.) Heller. H. australis Heller. 

 Mountains: Wyo. Utah N.M. Chihuahua. Submont. Mont. Je-S. 



3. S. microphylla Rydb. A low diffuse shrub, 3-10 dm. high; leaf -blades 

 spatulate-cuneate, 1-1.5 cm., rarely 2 cm. long, evenly serrate above the middle, 

 obtuse at the ar3ex, cuneate at the base; inflorescence small, 3-5 cm. long; sepals 

 about 1 mm. long, ovate, villous; petals broadly obovate or oval, a little exceed- 

 ing the sepals; stamens 20; carpels about 1.5 mm. long. H. microphyllus Rydb. 

 Mountains: Colo. Wyo. Utah; apparently also in Calif. Submont. Mont. 

 Je-Au. 



4. S. glabrescens (Greenm.) Rydb. A diffuse shrub, 6-12 dm. high; leaf- 

 blades cuneate-obovate, 11.5 cm. long, decurrent on the short petioles, evenly 

 toothed above the middle; inflorescence more or less compound, 3-6 cm. long; 

 the branches short and spreading; sepals ovate, 1.5 mm. long; petals white, oval, 

 2 mm. long; stamens 20; carpels 1.5 mm. long. Spiraea discolor glabrescens 

 Greenm. H. glabrescens Heller. Mountains: Ore. n Calif. Utah. Submont. 

 Mont. Je-Au. 



9. HORKELIA Cham. & Schlecht. 



Perennial herbs, with scaly rootstocks or caudices. Leaves pinnately com- 

 pound, usually with many leaflets. Inflorescence cymose-paniculate. Hypan- 

 thium deeply campanulate to saucer-shaped. Bractlets, sepals, and petals 5. 

 Petals strap-shaped, oblanceolate, obovate, cuneate, or obcordate, often unguicu- 

 late, white or light yellow. Stamens 10, inserted in the throat of the hypan- 

 thium; filaments dilated and more or less petaloid, persistent, triangular, subu- 

 late, with a distinct midrib. Receptacle generally conic or hemispheric, with 

 numerous pistils. Style long and slender, articulated to the achene and de- 

 ciduous. Ovule and seed inserted near the base of the style, pendulous and 

 anatropous. 



Plant less than 3 dm. high; petals 2-3 mm. long. 1. H. parviflora. 



Plant more than 3 dm. high; petals 36 mm. long. 



Leaflets ovate or oval, 2-3 cm. long; bracts generally exceeding the inflorescence. 



2. //. capitata. 



Leaflets obovate or cuneate, usually less than 2 cm. long; bracts shorter than the 

 inflorescence. 3. H. fusca. 



